Help with Eheim heater

[Rxb09a]

So I just bought a Eheim heater due to my other one breaking. I had it set at 78 and it kept rising to high 78s. So I followed the instructions and recalibrated it.

Since recalibrating it I turned it down to 77 and it’s now at 79.2 does anyone have any ideas or had this happen to them?

 

[Cory]

What size tank and how many watts is it?

 

[[Cameron]]

Check and make sure your heater is actually heating the water. The 80 degrees could be from items in the tank other than the heater. Next thing is to make sure your temperature probe is accurate. Calibrate it using the ice water method. Then use it to calibrate your heater in a 5g bucket. Afterwards, check and see if the tank temps stabilize. If they do not and you have ruled out other methods of heating the tank (lights, pumps, home heat registers, etc) then I would replace the heater.